Safety of US Nuclear Reactors Called into Question in New Report

A new report by the influential non-profit group National Resources Defense Council (NRDC) suggests that the US Nuclear Regulatory Commission is still not adequately protecting American nuclear reactors from the risk of hydrogen explosions such as the ones that crippled the Fukushima Dai-ichi nuclear campus three years ago. (Photo : Reuters )

In a severe loss-of-coolant scenario such as the one that triggered the meltdown at Fukushima after a March 11, 2011 earthquake and tsunami, uranium-filled fuel rods, made of zirconium, react with steam, producing tons of combustible hydrogen.

At the Fukushima campus, hydrogen accumulated and then detonated, breaching the reactor's containment structures and spewing radioactive material into the air, forcing evacuations and creating a nuclear incident that is still being dealt with to this day. Japanese authorities day it will take decades to fully decommission the Fukushima power station.

The NRDC reports that that the Nuclear Regulatory Commission is relying on outdated computer models that do not account for the sort of rapid gas build-up that triggered the Fukushima meltdown.

The NRDC contends that that the only safety measures in place are merely "token steps to address the problem" and that safety systems in place are just as likely to trigger an explosion as they are to prevent one.

"US reactors remain vulnerable to the threat of runaway hydrogen production and leakage in a severe nuclear accident, with little or no capacity to safely reduce or vent potentially explosive concentrations of this gas before it explodes and contaminates the surrounding region," said Christopher Paine, senior policy adviser in NRDC's nuclear program and contributing editor to the report.

Paine says that the US Nuclear Regulatory Commission has only designated the risk of hydrogen explosions as a third tier threat in their post-Fukushima response plan.

"It is clear from this report that it will be costly to maintain the safety of the aging reactors in the current US nuclear fleet, which will increasingly operate beyond their 40-year initial license terms," said Paine. "Nuclear power faces significant competition from lower-cost electricity sources, creating an unsettling tradeoff between economic viability and public safety."

Nine reactors were said to need to resolve one or two problems of "low safety significance." Another nine were "operating at a degraded level of performance."

Two other reactors rounded out the 20 that did most meet their objectives. Browns Ferry-1 in Alabama required "increased oversight due to a safety finding of high significance, which will include additional inspections to confirm the plant's performance issues are being addressed," NRC said.

According to the NRC, Fort Calhoun reactor in Nebraska "is currently under a special NRC oversight program distinct from the normal performance levels because of an extended shutdown with significant performance issues. The oversight panel cleared the unit to restart in December, but the plant will remain under special oversight until the panel returns it to the regular program. Therefore, the plant will not receive an annual assessment letter."